To give Sis time to compose herself, I brewed some coffee and handed it to her.
Warmth is especially comforting when you're feeling down.
As she sipped the hot coffee, I could see Sis regaining some calm.
"Mm..."
Sis mumbled to herself, pursing her lips as she searched for the right words to start.
Finally, she forced the words out, and the topic she brought up was completely out of left field.
"Ihyeon. Do you know why magical girls retire?"
"Magical girls retiring?"
I paused mid-sip, sorting through the question in my head.
"Maybe they get tired of fighting monsters or get scared, or they just want to live their own lives. Probably changes in their environment or mindset are the main reasons?"
Those were the official reasons given for magical girls' retirements.
It was heartbreaking that girls not even old enough to be adults had to fight disasters like monsters, but for now, they were the best option we had.
The nature of magical power as an energy source was still unclear, and using the military led to massive casualties and frequent failures in subjugation.
The world was barely holding together on thin ice, relying on teenage girls, but it hadn't grown so harsh as to force them to keep fighting past retirement.
"Changes in environment or mindset are part of it, like you said, but to be precise... every magical girl retires for a reason."
"A common reason?"
Sis rubbed her mug of coffee between her hands and hesitantly opened her mouth.
"It's because magical girls turn into defective products the more they use their magic or magical power. By the time they become adults, the defects are too severe to keep fighting."
The retirement reason Sis confessed was beyond anything I'd imagined.
"Defects?"
"Yeah. Defects. When a teenager's unstable sense of self solidifies into adulthood, they can't hold out without retiring."
"Is there some kind of restriction that comes with using magic?"
If so, then her transforming into her magical girl form in front of me earlier carried risks, and my face paled at the thought.
Sis seemed to read my mind and smirked, adding,
"Transforming into the magical girl form isn't that straining. Problems start when you ramp up the magic power enough to fight monsters. Or at least... that's the theory, since the exact cause hasn't been pinpointed."
She gave an easy example: like how stretching before exercise doesn't hurt you.
"Then what's causing it? Are these defects really that dangerous?"
"Yes."
Sis affirmed it firmly, without a trace of her usual timid, downcast demeanor.
"It's just speculation, but it's probably the price of the transcendent power they wield. The defects become unbearable, so they retire the moment they hit adulthood."
Suddenly, I recalled news stories about retired magical girls saving people from fires or car accidents right before disaster struck.
Those women had used magic despite the risks of their defects, which made it even more astonishing.
"Sis retired because of these defects too, right?"
It was a stupid question.
The reason Sis had holed up in her room after turning twenty.
I could sense it stemmed from some inexplicable risk called a defect.
'So that's what it was...'
She'd always been a bit timid and withdrawn since our school days, but never so twisted as to cut herself off from the world.
As expected, Sis nodded in affirmation.
Seeing the woman I loved looking so downcast with some heavy burden, anger welled up unbidden. I started to ask about her defect but quickly clamped my mouth shut.
"..."
"D-don't worry. I wasn't planning on hiding it from you too."
Even as she said that, her hands gripped the mug so tightly her knuckles turned white, her body trembling as she fought to hold it together.
I wanted to tell her she didn't have to share if it was that painful, but it was clear she'd gathered her courage for this moment and come here. So I just took her hand silently.
Her shaking hand gradually steadied in mine.
"Ihyeon. Th-that... l-listen, listen to meee..."
"Sis, aren't you worrying too much? I'm not that hopeless a guy."
Sis, who hadn't stuttered at all until moments ago, now stammered anxiously.
But she seemed to decide she couldn't hold back anymore and finally confessed her defect.
"Ihyeon. My defect is... h-h-heat, heat..."
"Heat?"
"It's estrus...!"
Sis hung her head, her voice trailing off into a mumble as she confessed her defect.
I barely caught the end, but "estrus" rang clear as day.
Estrus.
The term for when you can't control your sexual impulses.
"...Estrus??"
"Kkh, kkhueeeek!!!"
The word slipped out, and Sis slammed her head into the table with a thud, mortified to death.
"S-so... that's why you've been holed up in your room for five years without coming out...?"
"I-I thought I'd pounce on some guy... every day my libido boils over, and I can't hold back—I'd end up jumping a man...!"
Kang Ihyeon felt like he'd been whacked on the back of the head.
If Sis had been more free-spirited about relationships, or had a bolder, more flexible personality, it might not have been such a big deal...
'No, no, no. Who am I kidding?!'
The way she'd been about to pounce on me earlier was the picture of depravity itself.
A former magical girl unable to control her lust and assaulting random men?
It would be prime gossip fodder for those who already distrusted magical girls.
"S-Sis... s-so... you couldn't suppress the estrus anymore, so you went for me, the guy you at least like...? Is that it?"
"Kiiiiieeeek!!!"
Sis let out a bizarre screech like tires skidding on brakes and clutched her hair like she wanted to rip it all out.
"R-right now, I mean... ah, um... even now, I just can't hold back, I want to..."
A magical girl's estrus defect was every man's dream, so rude or not, I had to ask.
"N-no! Absolutely not right now!!!!"
Sis's desperate shout carried real anguish—she couldn't bear being mistaken for a slut.
I could feel the other "me" between my legs drooping in disappointment.
"It's like PTSD for soldiers! Not like I want to jump every guy like some bitch in heat...!"
Bam!
In her frantic excuse, Sis slammed her head into the table again, as if questioning her own nonsense.
"Sis?!"
"I-I'm fine... just a rush of blood to the head."
Her forehead was swollen bright red, on the verge of splitting open, but I kept my mouth shut.
"In my case, I'd suppressed the defect for so long that the backlash hit hard. It should be okay for a while."
Sis mumbled "probably" at the end.
"It's fine! If that's the defect, you're more than welcome...! Ahem! I can take care of you! As your boyfriend—no, as your husband!"
"Husband...?!"
Now I understood why she'd suddenly blurted out wanting me to be her husband.
If she'd just told me about the defect sooner, we wouldn't have wasted five years going in circles. Part of me regretted it, but I was so overjoyed I wanted to hug her and spin her around.
But Sis only looked more guilty and apologetic.
"Sorry, Ihyeon. Of all things, making you deal with this right after your dad's funeral..."
Her casual remark sent my sky-high elation plummeting through the earth's core.
Cold sweat poured down my back in buckets.
"N-no... it's okay. Dad would understand. As a Care Supporter, he'd probably even praise me for it?"
Dad, I'm sorry!!!
Kang Ihyeon had always thought he'd been a dutiful son, but at the end, he'd pulled this insane stunt. He apologized from the depths of his heart.
'No wonder Dad looked at me pitifully sometimes, muttering about the thing between my legs.'
Dad had known Sis's situation, and that we both had feelings for each other.
If I'd manned up and become Se-ah Sis's boyfriend, deepening our bond, her estrus defect could've been managed easily.
I resented him for not giving me a straight hint instead of beating around the bush, but after committing such massive filial impiety, I had no ground to stand on.
"Do you think your dad would forgive me for nearly pouncing on his son right after the funeral? He was such a good man. He tried to care for someone like me to the end."
"Dad did?"
"Yeah. I couldn't hold back once and almost jumped him, so he shot me with a suppression bullet."
Sis casually pointed at the pistol on the living room table as she spoke.
Hearing that, I could only scream internally at my already-gone dad: What the hell have you been up to?!
Shooting a 25-year-old woman to subdue her? What kind of nonsense was this?
"So Dad shot you?"
"Yeah. One of a Care Supporter's duties is to shoot magical girls with those if their defects go berserk. If suppression fails..."
Sis glanced at the two magazines on the table—one different from the other.
I could vaguely guess the meaning of the differently glowing magazines, and goosebumps prickled my arms.
"Just estrus?"
"Just?! What do you mean 'just'?! Do you have any idea how hard that is?! Rubbing like crazy down there without breaking your hymen until it goes numb...!"
Bam!
Sis smashed her head into the table hard enough to whistle through the air, clamping down on her runaway mouth.
Blood trickled across the table, but this time, she had no choice but to shut up.
No words would come.
In the heavy silence that hurt my chest, Sis spoke from her bowed position, her voice damp and ghostly, like a specter crawling from hell.
"Don't assume just because it's mine. The other magical girls' defects are beyond imagination. It's rude."
"Sorry."
I apologized sincerely.
Sis didn't have the courage to lift her head and continued in that position.
"So take over from your dad as my Care Supporter. Otherwise, I'll never leave this room."
The words "just marry me" nearly escaped, but then I imagined some other Care Supporter meeting Sis regularly.
'Why am I suddenly pissed?'
A rational, upstanding one like Dad wouldn't be an issue, but what if he had ulterior motives?
I absolutely couldn't leave Sis's care to another man.
"Sis! Don't worry! No matter what, I'll become your Care Supporter and look after you for life."
Years later, I learned female Care Supporters existed and asked Sis why she hadn't switched to one.
At my sharp remark, Sis fidgeted guiltily and made an excuse.
"Strangers make me uncomfortable."
It was such a quintessentially Sis reason that I was left speechless.